Fix clang warnings on architectures with a 64-bit long

Fix clang warnings on architectures with a 64-bit long

On most systems where we compile e2fsprogs, the u64 type is an
unsigned long long.  However, there are platforms (such as the
PowerPC) where a long 64-bits and so u64 is typedef'ed to be unsigned
long instead of a unsigned long long.  Fix this by using explicit
casts in printf statements.  For scanf calls, we need to receive the
value into a unsigned long long, and then assign it to a u64, after
doing range checks.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>